Passport P-10W UHF Manual Del Usuario página 11

To replace the battery:
Open the battery compartment by pressing down on the two tabs at the top
of the battery compartment. The door will hinge open.
The battery is "spring loaded" behind an interior panel. Remove this panel
by sliding it upwards.
Remove the battery by pulling it out of the compartment. Replace the battery
with another. The terminals on the battery should be on the "top" as you
slide it into the compartment.
Press the battery into the unit and replace the interior rear panel.
Close the compartment door. Lift up the two tabs until they "click" into
place.